Why tuples use parentheses ()'s instead of something else like <>'s?

[Alex Martelli]

seberino at spawar.navy.mil <seberino at spawar.navy.mil> wrote:

> Tuples are defined with regards to parentheses ()'s as everyone knows.

Well, then, "everyone knows" wrong:

x = 1, 2, 3

x is a tuple.  The _commas_ make it one -- parentheses don't matter.

An _empty_ tuple uses parentheses, (), as there's nowhere to put commas;
and you need parentheses AROUND the tuple-with-commas when the commas by
themselves would be interpreted otherwise (function definition and call,
except clause).  But generally, the commas are what mattes.


> This causes confusion for 1 item tuples since (5) can be interpreted
> as a tuple OR as the number 5 in a mathematical expression

Nah: no commas, no tuple.  To set x to a one-item tuple:

x = 5,

feel free to put useless parentheses around the RHS, they don't hurt.
But the comma MUST be there.

> Wouldn't it have been better to define tuples with <>'s or {}'s or
> something else to avoid this confusion??

Instead of commas?  I think it would look weird.

> Perhaps ()'s are a good idea for some other reason I don't know?

They're somewhat overloaded, and so are commas.  There just isn't enough
neat-looking punctuation in the ASCII character set.


Alex